Enhance: generate 32-bit seeds

SeedVR2VideoUpscaler (the new Sharpen / Rescue templates) rejects seeds
above 2^32 - 1 at validation, and the 52-bit seeds made every job fail with
"Value ... bigger than max of 4294967295: seed". 32 bits is still plenty of
variety for the Fibo templates.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/enhance/service.rs

@@ -16,7 +16,7 @@ use serde::{Deserialize, Serialize};
 use super::comfy::{ApproveError, ComfyClient, ComfyError, HistoryEntry, Staged, SubmitError};
 use super::config::{EnhanceConfig, Loaded, PromptMode};
 use super::path_map::PathMap;
-use super::template::Template;
+use super::template::{Template, random_seed};
 use crate::database::enhance_dao::{
     EnhanceJobDao, EnhanceJobRow, JobUpdate, RecentPrompt, STATUS_APPROVED, STATUS_EXPIRED,
     STATUS_FAILED, STATUS_QUEUED, STATUS_READY, STATUS_RUNNING, STATUS_UNAVAILABLE,
@@ -314,9 +314,7 @@ impl EnhanceService {
             None => None,
         };
         let filled = template
-            .fill(&source, prompt, reference_path.as_deref(), &mut || {
-                rand::random::<u64>() >> 12
-            })
+            .fill(&source, prompt, reference_path.as_deref(), &mut random_seed)
             .map_err(|e| EnhanceError::BadRequest(e.0))?;
 
         if !self.probe_now().await {

src/enhance/template.rs

@@ -285,6 +285,13 @@ fn links_to(v: &Value, id: &str) -> bool {
     matches!(v.as_array().map(Vec::as_slice), Some([Value::String(s), Value::Number(_)]) if s == id)
 }
 
+/// A fresh seed for one job. 32 bits: some nodes cap their seed there
+/// (SeedVR2VideoUpscaler's max is 2^32 - 1), and it's plenty of variety for
+/// the ones that take 64.
+pub fn random_seed() -> u64 {
+    u64::from(rand::random::<u32>())
+}
+
 fn is_seed_input(key: &str) -> bool {
     key == "seed" || key == "noise_seed" || key.ends_with(".seed")
 }
@@ -401,12 +408,22 @@ mod tests {
         assert!(a > 1000 && b > 1000 && a != b);
         assert_ne!(a, 774744764437710);
         // Two fills with a real RNG differ.
-        let mut rng = || rand::random::<u64>() >> 12;
+        let mut rng = random_seed;
         let x = t.fill("p", None, None, &mut rng).unwrap();
         let y = t.fill("p", None, None, &mut rng).unwrap();
         assert_ne!(input(&x.prompt, "5", "seed"), input(&y.prompt, "5", "seed"));
     }
 
+    #[test]
+    fn random_seeds_fit_seedvr2s_u32_limit() {
+        // SeedVR2VideoUpscaler rejects seeds above 2^32 - 1 at validation.
+        let t = load(RESTORE, PromptMode::Append).unwrap();
+        for _ in 0..200 {
+            let f = t.fill("p", None, None, &mut random_seed).unwrap();
+            assert!(input(&f.prompt, "5", "seed").as_u64().unwrap() <= u64::from(u32::MAX));
+        }
+    }
+
     #[test]
     fn force_approval_even_if_the_export_had_it_off() {
         let off = RESTORE.replace("\"require_approval\": true", "\"require_approval\": false");